Mu-opioid receptor-dependent changes in social reward across adolescence in mice

Abstract In humans, adolescence is a time of dynamic behavioral changes, including a transient decrease in affect associated with being among family members. Here, we found that the reward value of interactions with siblings in adolescent male mice followed a similar course to that in humans: high in preadolescence, a decrease in mid-adolescence and a return to the initial level in late adolescence, as observed in the social conditioned place preference task. The observed change was specific to social interaction, as the rewarding effect of cocaine was actually increased during mid-adolescence. Strikingly, treatment with a selective mu-opioid receptor antagonist, cyprodime, increased socially conditioned place preference in mid-adolescent mice, but not in older animals. Taken together, these data show similarities between mice and humans in developmental changes in sensitivity to the rewarding effects of interactions with familiar kin and demonstrate the involvement of endogenous opioid signaling in shaping adolescent social behavior.